The present invention pertains generally to roll forming machines having a multitude of roll sets for the progressive shaping of continuous sheet metal fed between the roll sets.
U.S. Pat. Nos. 3,710,607; 3,788,155 and 4,020,666 show roll forming machines for the production of metal siding for application to the exterior of houses. A continuous metal strip is fed from a source such as a roll of such material through upper and lower roll sets to progressively impart configurations to the side margins of the material. U. S. Pat. No. 3,788,115 discloses an extension for attachment to such a machine. The extension swings about a horizontal axis into and out of an operable position at the discharge end of the roll forming machine. Such an extension enabled the optional forming of bends along the central portion of the metal strip, but had a tendency to become misaligned with the fixed roll sets of the machine. Roll alignment is critical to the production of precision made metal siding for homes. In addition to the recurring alignment problems, the extension was of bulky configuration, considerable weight, costly to fabricate and attach to the roll forming machine. Accordingly, once in place, the extension was not easily interchanged with a second extension. It is now common to impart shape to the continuous central area of the siding strip. Siding contractors heretofore offered siding with or without a shaped central area. A machine once equipped with a roll equipped extension was not easily modified by the substitution of a replacement set of auxiliary rolls.